System and method for defining an urgency class of a disorder appearing in a communication system station

ABSTRACT

A system and method for determining an urgency class of a disturbance occurring in a base station of a cellular communication system. A list of possible disturbances that can emerge during the functioning of the base station and the preliminary urgency classes determined for the disturbances concerned is maintained in a memory. In order to enable more accurate urgency classification, a preliminary urgency class is searched out from the memory corresponding to disturbances in question. An alarm urgency class is conditioned with the communications state of the base station by detaining a less urgent class than the preliminary urgency class when the communications state of the base station is peaceful (i.e., not busy). When the communication state of the base station is busy, a more urgent class than that of the preliminary urgency class is determined for the alarm.

This invention relates to a method for defining an urgency class of adisorder appearing in a base station, in which method a list ismaintained in a memory means about the disorders, which may occur in thebase station operation, and of the preliminary urgency classesdetermined for the disorders in question. The invention relates also toa cellular radio system including a base station, comprisingtransmitter-receiver means for forming a connection with radio units inthe radio covering region, memory means for maintaining the list aboutdisorders that can occur in the base station operation and also of thepreliminary urgency classes determined for the disorder concerned, andalarm means adapted to search in connection with the base station'smalfunction from the memory means the urgency class corresponding thedisorder in question as well as to send the alarm message indicating theurgency class to the system operator.

The invention relates particularly to base stations of cellular radiosystems and handling of alarms sent from these to the operator. It isalready known to utilize for example in connection with the alarmhandling of base stations of the NMT (Nordic Mobile Telephone) cellularradio system an urgency classification based on the quality of the faultor disorder emerged in the base station, i.e. the faults that can occurin the base stations have been classified in advance according to theneed of urgent measures. When a fault or disorder of certain type thenemerges, the alarm system checks first from the memory where the urgencyclass the disorder in question belongs. After this an alarm is given tothe system operator, whereat the urgency class found from the memory isindicated to the operator. The urgency class reveals then to theoperator, how he should deal with the alarm or does this mean that theservice personnel should visit immediately the base station installationplace, or is it possible to postpone the visitation for instance to thenext working day.

The most significant weakness of the above-mentioned known solution is,that if the same disturbance emerges in two base stations, the samealarm is given to the system operator, though the disturbances may haveentirely different meaning concerning the base station communicationsthroughput. Or if a faulty base station is situated for example alongwith a busy highway and half of its capacity is lost due to amalfunction, the base station concerned requires naturally much quickermaintenance than for instance in the case, if a base station is a skiresort loses half of its capacity during summer months, when the resortis closed. In these above-mentioned cases both base stations in knownsystems, however, transmit the alarms belonging to the same urgencyclass.

The object of the present invention is to solve the above-mentionedproblem and to provide a better method for making the urgencyclassification of base station alarms. This object is achieved by themethod according to the invention, which is characterized in that apreliminary urgency class corresponding the disturbance in question issearched from the memory means and the alarm urgency class isproportioned to the communications situation of the base station bydetermining a less urgent class than the preliminary urgency class forthe alarm, if the base station communications situation is at rest, andby determining a more urgent class than the preliminary urgency class,if the base station communications situation is busy.

The invention is based on the idea, that when it is observed in thedisturbance urgency classification in addition to the emergedmalfunction type also the base station communications situation, or howmany phone calls through the base station concerned has lately beenmade, a method is achieved enabling better than before to sieve out thealarms that do not imply immediate actions. The most outstandingadvantage of the method according to the invention comprises thereforethe fact, that the emergency classification is based on the actualrecent communications situation of the base station, which gives abetter conception of the moment, when the service personnel really mustdo immediate actions.

The invention concerns also relates to a cellular radio system, in whichthe method according to the invention can be adapted. The cellular radiosystem according to the invention is characterized in that the alarmmeans have been supplied to check the communications situation of thebase station before sending the alarm message and to change thedisturbance urgency class as less urgent, if the communicationssituation of the base station is peaceful, or correspondingly to changethe disturbance urgency class as more urgent, if the communicationssituation of the base station is busy.

The invention will be described in the following according to apreferred embodiment of the invention with reference to the enclosedfigures, in which:

FIG. 1 shows a flow diagram of the first advantageous embodiment of themethod according to the invention; and

FIG. 2 shows a block diagram of the first advantageous embodiment of thecellular radio system according to the invention.

FIG. 1 shows a flow diagram of the first advantageous embodiment of themethod according to the invention. A malfunction occurs in the block Ain the base station of the FIG. 1. In question can be for instance amalfunction, due to which one of the base station receivers ceases tofunction.

In the block B the preliminary urgency class, that has determined inadvance for the malfunction concerned, is searched from the table to bemaintained in the memory means. Let us assume that the urgency classdetermined in advance is for instance A4, which means that thedisturbance in question does not require any immediate attention.

In the block C the communications situation W of the base station iscleared out. The base station communications situation is clearedpreferably once a day, whereat the value indicating the communicationssituation is deposited to the memory. In addition to this thecommunications situation can also be defined always, when a malfunctionin occurring in the base station. The operator can, if he so desires,determine manually the base station communications situation bydepositing the value representing it to said memory. The system canalternatively calculate automatically the communications situation W,whereby in the beginning it is explained, how much of the base stationcommunications capacity has recently been used. This is performed forexample in such a way, that the maximum sum of one-hour erlangs in anderlangs out values obtained from the BST-measurements during sevenpreceding days is searched out from the memory (one erlang corresponds asituation, in which one of the radio channels of the base station hascontinuously been in use during one hour).

If the results of the BST-measurements are not for some reason availablewhen the communications are cleared out, it is possible to use forinstance the equation W=0.5 * L2* max., where max.=the maximum number ofchannels available for a base station in order to form the calculatorycommunications situation.

Let us assume that for example W=12 has been obtained as thecommunications situation value W. The received value W is compared withthe limit values L1 and L2 determined in advance by the operator, whichvalues can for instance be L1=6 and L3=10, and if then:

W<L1, the base station communications situation is peaceful,

L1≦W<L2, the base station communications situation is normal,

W≧L2, the base station communications situation is busy.

If it turns out, that the communications situation is busy, transfer ismade from the block C through the block D to the block F. In the block Fit is searched from the alarm definition table a more urgent class thanthe preliminary urgency class for a busy base station, in which thefault type in question is occurring. Alternatively a class, that is oneclass more urgent than the preliminary urgency class, or e.g. A3, cansimply be selected for the alarm.

If on the contrary it turns out that the communications situation ispeaceful, transfer is made from the block C through the block E to theblock G. In the block G it is searched from the alarm determinationtable a less urgent class than the preliminary urgency class for thepeaceful base station, in which the fault type in question occurs.

Alternatively an urgency class that is one class lower than thepreliminary urgency class, or e.g. A5, can simply be selected for thealarm.

If it turns out that the base station communications situation isnormal, transfer is made from the block C through blocks D and E to theblock H, where the preliminary urgency class is selected as the finalurgency class.

From the blocks P, G and H transfer is made to the block I, where analarm message known as such is sent to the operator indicating to theoperator the urgency class of the malfunction in question.

FIG. 2 shown a block diagram about the first preferred embodiment of thecellular radio system according to the invention. The cellular radiosystem presented in FIG. 2 may for instance be a NMT-system. In FIG. 2has been shown a mobile telephone exchange (MTX) 3 that is in acommunications connection with two base stations (BST) 1 and 2. Thecontrol room 5 of the operator is in connection with the operating andmaintenance computer 4 associated with the mobile telephone exchange.

The operator has in advance deposited into the memory means 5, which maycomprise for example a hard disk of the operating and maintenancecomputer 5, a list concerning the disturbances, which may occur in theoperation of the base stations 1 and 2, and also the urgency class ofthese disturbances. Further on, it has been deposited to the memorymeans 5 information concerning the communications situation of the basestations, or among other things the values L1 and L2, by which thecommunications situation of the base stations will be classified.

When e.g. in the base station 1 occurs a disturbance, the operating andmaintenance computer 4 finds this immediately out, whereby it searchesfrom the memory means 5 its preliminary urgency class (for example A4),that the operator has determined for the disturbance in question.Alternatively the alarm message sent from the base station to theoperating and maintenance computer indicate the preliminary urgencyclass.

When the preliminary urgency class has been cleared, the computer 4finds out the base station communications situation by searching fromthe memory means 5 the maximum sum W of hour erlangs in and erlangs outvalues of the base station received from the BST-measurements of sevenpreceding days (which sum value it continuously maintains), and also theclassification limits L1 and L2 determined by the operator.

Based on values W (for instance 12), L1 (for instance 6) and L2 (forinstance 10) the computer states, that the communications situation ofthe base station 1 is busy. Therefore it selects for the emergeddisturbance an urgency class (e.g. A3), that is more urgent than thepreliminary urgency class. When the urgency class has been selected, theoperating and maintenance computer 4 sends in a known as such manner analarm message to the control room 6 of the operator, whereby the alarmmessage in question indicates the urgency class of the malfunction tothe operator.

It should be understood, that the preceding description and the figuresconnected with it are only intended to illustrate the present invention.It is therefore obvious that the determination of the urgency class ofthe disturbance may alternatively take place entirely in some other partof the system, as e.g. in the base station, though in the precedingexample it has been presented, that the urgency classification takesplace in the mobile telephone exchange. To the persons skilled in theart may other variations and modifications of the invention will also beobvious without deviating from the scope and spirit of the invention setforth in the enclosed claims.

We claim:
 1. A system for determining an urgency class of a disturbanceoccurring in a communication station subjected to a communication load,comprising:first defining means for defining a plurality of disturbancetypes, each of said plural disturbance types corresponding to a uniquecommunication station disturbance; second defining means for defining aplurality of preliminary urgency classes, each of said pluralpreliminary urgency classes corresponding to one of said pluraldisturbance types, wherein each of said plural preliminary urgencyclasses is of a particular severity level indicative of a severity ofsaid corresponding disturbance type; memory means operable to store saidplurality of disturbance types and said plurality of urgency classes;and first control means for: (i) identifying, when a particularcommunication station disturbance occurs, a corresponding particulardisturbance type of said plural disturbance types; (ii) identifying aparticular preliminary urgency class corresponding to said identifiedparticular disturbance type; and (iii) determining whether thecommunication load of the communication station is one of a low load anda high load, and(A) when the communication load is determined to below,(1) decreasing said severity level of said identified particularpreliminary urgency class to a low severity level, and (2) generating anurgency class output of said low severity level, so that said urgencyclass output is indicative of said severity of said identifiedparticular communication station disturbance and of the magnitude of thecommunication load; and (B) when the communication load is determined tobe high,(3) increasing said severity level of said identified particularpreliminary urgency class to a high severity level, and (4) generatingan urgency class output of said high severity level, so that saidurgency class output is indicative of said severity of said identifiedparticular communication station disturbance and of the magnitude of thecommunication load.
 2. The system of claim 1, wherein said control meansfurther comprises:measuring means for measuring, over a predeterminedtime period, a current communication load level of said communicationstation; and comparing means for comparing said current communicationload level to a first and a second predetermined load value, and (i)when said current communication load level is lower than said firstpredetermined load value, indicating that the communication load is alow load, and (ii) when said current communication load level is higherthan said second predetermined load value, indicating that thecommunication load is a high load.
 3. A communication system monitoredby a system operator, comprising:a communication station having areceiver and a transmitter for communicating with remote mobilecommunication units in a predetermined coverage area, wherein saidcommunication station is subjected to a communication load; firstdefining means in the communication station for defining a plurality ofdisturbance types, each of said plural disturbance types correspondingto a unique disturbance that may occur in said communication station;second defining means in the communication station for defining aplurality of preliminary urgency classes, each of said pluralpreliminary urgency classes corresponding to one of said pluraldisturbance types, wherein each of said plural preliminary urgencyclasses is of a particular severity level indicative of a severity ofsaid corresponding disturbance type; memory means in the communicationstation operable for storing said plurality of disturbance types andsaid plurality of urgency classes; and alarm means in the communicationstation for: (i) identifying, when a particular disturbance occurs insaid communication station, a corresponding particular disturbance typeof said plural disturbance types; (ii) identifying a particularpreliminary urgency class corresponding to said identified particulardisturbance type; and (iii) determining whether the communication loadof said communication station is one of a low load and a high load,and(A) when the communication load is determined to be low,(1)decreasing said severity level of said identified particular preliminaryurgency class to a low severity level, and (2) transmitting an urgencyclass alarm signal of said low severity level to the system operator topermit the system operator to assess said alarm signal; and (B) when thecommunication load is determined to be high,(3) increasing said severitylevel of said identified particular preliminary urgency class to a highseverity level, and (4) transmitting an urgency class alarm signal ofsaid high severity level to the system operator to permit the systemoperator to assess said alarm signal.
 4. The system of claim 3, whereinsaid alarm means further comprises:measuring means for measuring, over apredetermined time period, a current communication load level of saidcommunication station; and comparing means for comparing said currentcommunication load level to a first and a second predetermined loadvalue, and (i) when said current communication load level is lower thansaid first predetermined load value, indicating that the communicationload is a low load, and (ii) when said current communication load levelis higher than said second predetermined load value, indicating that thecommunication load is a high load.
 5. The system of claim 4, whereinsaid measuring means comprises means for(i) measuring a plurality ofsums of erlangs in values and erlangs out values over said predeterminedtime period; (ii) storing said measured plural sums in said memorymeans; (iii) determining a maximum value sum of said measured pluralsums; and (iv) setting said current communication load level to saidmaximum value sum.
 6. The system of claim 5, wherein said predeterminedtime period is seven days.
 7. A method for determining an urgency classof a disturbance occurring in a communication station subjected to acommunication load, comprising the steps of:(a) defining a plurality ofdisturbance types, each of said plural disturbance types correspondingto a unique communication station disturbance; (b) defining a pluralityof preliminary urgency classes, each of said plural preliminary urgencyclasses corresponding to one of said plural disturbance types, whereineach of said plural preliminary urgency classes is of a particularseverity level indicative of a severity of said correspondingdisturbance type; (c) storing said plurality of disturbance types andsaid plurality of urgency classes; (d) identifying, when a particularcommunication station disturbance occurs, a corresponding particulardisturbance type of said plural disturbance types; (e) identifying aparticular preliminary urgency class corresponding to said identifiedparticular disturbance type; and (f) determining whether thecommunication load of the communication station is one of a low load anda high load, and(A) when the communication load is determined to below,(1) decreasing said severity level of said particular preliminaryurgency class to a low severity level, and (2) generating an urgencyclass output of said low severity level, so that said urgency classoutput is indicative of said severity of said particular communicationstation disturbance and of the magnitude of the communication load; and(B) when the communication load is determined to be high,(3) increasingsaid severity level of said particular preliminary urgency class to ahigh severity level, and (4) generating an urgency class output of saidhigh severity level, so that said urgency class output is indicative ofsaid severity of said particular communication station disturbance andof the magnitude of the communication load.
 8. The method of claim 7,wherein said step (f) further comprises the steps of:(g) measuring, overa predetermined time period, a current communication load level of saidcommunication station; and (h) comparing said current communication loadlevel to a first and a second predetermined load value, and(C) when saidcurrent communication load level is lower than said first predeterminedload value, indicating that the communication load is a low load, and(D) when said current communication load level is higher than saidsecond predetermined load value, indicating that the communication loadis a high load.